Isn't using find with retro awkward?

[jam]

On Wed, 16 Feb 2011 20:24:36 +0100, Andrej Mitrovic wrote:

> The only thing I could come up with is exhausting the entire range to
> get the length of a bidirectional range. But that's inefficient. Anyway
> here's the dull thing:
> 
> import std.stdio;
> import std.range;
> import std.array;
> 
> R findBack(alias pred = "a == b", R, E)(R haystack, E needle)
>     if (isBidirectionalRange!R)
> {
>     size_t index;
>     bool found;
>     auto saved = haystack;
> 
>     foreach (item; retro(haystack))
>     {
>         if (item == needle)
>         {
>             found = true;
>             index++;
>             break;
>         }
>         index++;
>     }
> 
>     if (found)
>     {
>         size_t newIndex;
>         while (!haystack.empty)
>         {
>             newIndex++;
>             haystack.popBack;
>         }
> 
>         newIndex -= index;
>         while (!saved.empty && newIndex)
>         {
>             saved.popFront;
>             newIndex--;
>         }
>     }
> 
>     return saved;
> }
> 
> void main()
> {
>     auto orig = [4, 0, 4, 0];
>     auto result = findBack(orig, 4);
> 
>     assert(array(result) == [4, 0]);
> 
>     result.front = 10;
>     assert(orig == [4, 0, 10, 0]);
> }
> 
> You'll have to forgive me but I have yet to study algorithms properly.
> :)

import std.stdio,std.algorithm,std.range;

void main()
{
    auto a = [5,1,2,3,4,5,1];
    auto index = countUntil(retro(a),5);
    writeln(a[a.length-1-index .. a.length]);
}

outputs:

[5,1]

but yeah, it is a little awkward.